High-speed printer with drift compensated cable for carriage

ABSTRACT

A high speed printer in which the carriage carrying a printing wheel is coupled to a servo controlled driving motor having intermittent motion. The motor drives a helically grooved pulley which has attached to it left and right cable segments of equal length. The other ends of the cable segments are attached to the movable carriage. During movement of the carriage the total length of each cable segment remains constant and equal and provides protection against temporary mechanical drift.

tlnited ttes atent 1191 1111 3,872,960 Gabor Mar. 25, 1975 HlGH-SPEEDPRINTER WITH DRIFT 3,011,034 11/1961 Lzlvianzl et a1. 74/8922 xCOMPENSATED CABLE FOR CARRIAGE 3,044,312 7/1962 3,168,182 2/1965 Bernardet a1. 197/49 Inventor: Andrew Gabor, lle, 0111f. 3,273,408 9/1966 Nagelet 111 74/8922 x [73] AssigneeZ Xerox Corporation, Stamford, 3,374,8733/1968 Takenaka 197/49 Conn. I Primary E.\'aml'ner-Edgar S. Burr [2'2]F1led: Feb. 25, 1972 [21] Appl. No: 229,397 [57] ABSTRACT A high speedprinter in which the carriage carrying a [52] Cl 197/531 74/892 197/555printing wheel is coupled to a servo controlled driving 197/601 {97/82motor having intermittent motion. The motor drives a [51] Int. Ll B411l/54 helically groove-d pulley which has attached to i left [58 Fleld 01Search 197/49, 53, 55, 18, 60, and right Cable segments of equal length.The other 197/82? 74/1071 89-22 ends of the cable segments are attachedto the mov able carriage. During movement of the carriage the [561References cued total length of each cable segment remains constantUNITED STATES PATENTS and equal and provides protection againsttemporary 2,757,775 8/1956 Hickerson 197 49 hanical drift. 2,831,4244/1958 MacDonald 1 197/49 X 2,859,629 11/1958 Parker et a1. 197/49 xClams 5 Drawmg Flgures PATENTEI] HARE 5 I975 H V Exmanna am HIGH-SPEEDPRINTER WITH DRIFT COMPENSATED CABLE FOR CARRIAGE BACKGROUND OF THEINVENTION The present invention is directed to a high-speed printer witha drift compensated cable for driving a carriage.

In printing devices of, for example, the Teletype or IBM Selectric type,it is necessary to convert the rotary motion of a drive shaft of a motorto linear carriage motion. One solution is a lead screw. This must bemade heavy to avoid windup and thus presents a high inertia to thesystem.

Cables and belts have also been used. These are normally unsuitable whenthe carriage is intermittently moved with high acceleration anddeceleration because of the resultant mechanical drift which causesmisregistration.

OBJECT AND SUMMARY OF THE INVENTION It is, therefore, an object of thepresent invention to provide a drift compensated cable for use indriving the carriage of a high-speed printer.

In accordance with the above object there is provided a high-speedprinter for printing on a record medium comprising a movable carriagefor carrying a printing unit along a predetermined line of printing withrespect to the record medium. Means for intermittently transporting thecarriage and printing unit to stationary printing positions along theline of printing is provided. The carriage is movable from a centerposition to extreme left and right positions. The transporting meansincludes a motor. Pulley means are driven by the motor. Cable meanscouple the pulley means to the carriage, The cable means are dividedinto two segments of equal length, each of the segments having an endaffixed to the pulley means. The pulley means have peripheral wrappingsurfaces for wrapping equal lengths of the two segments on said surfaceswhen the carriage is in the center position. The pulley meansrespectively accommodate a substantially greater length of one segmentthan the other when the carriage is is one of the extreme positions.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a plan view of a printerembodying the present invention;

FIG. 2 is a perspective view of the cable drive portion of FIG. 1;

FIG. 3 is an enlarged plan view of a pulley of FIG. 2;

FIG. 4 is an enlarged cross-sectional view of a portion of FIG. 2; and

FIG. 5 is an enlarged view of another portion of FIG. 2.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to FIG.1, an overall plan view of the printer of the present invention isillustrated which is contained within a frame 10. The printer includes aplaten or roller 11 which carries the paper or record medium. This isprinted upon by a print wheel 12 carried by carriage 13. Print wheel 12is of the type having a number of radially extending spokes with thetype element being on the periphery of the spokes. Printing occurs whena hammer 14 impacts the particular type element which has beenpreviously positioned. Details of printing wheel 12 and its operationare disclosed and claimed in a copending application entitled High SpeedPrinter with Intermittent Print Wheel and Car riage Movement, Ser. No.229,314, filed Feb. 25, 1972, now abandoned, in the name of Andrew Gaborand assigned to the present assignee.

Printing wheel 12 is carried along a predetermined line of printingalong platen 11 by carriage 13. The carriage itself is mounted forlinear movement on rods 16 and 17. The carriage includes a ribboncartridge 18, which has an inked ribbon l9 driven by a stepping motor21, and a vertical paper feed assembly 20.

Carriage 13 is intermittently transported to various stationary printingpositions along the line of printing by a motor 22. This motor isactually part of a servo control system; mounted on its shaft 15 is arotary disc 23 adjacent a fixed disc 24. As discussed in the abovecopending application a series of radial parallel metal conductors arepresent on the discs and provide position signals for the servo system.

A pulley 26 is also mounted on shaft 15. Motor 22 drives carriage 13 bycable means indicated generally as 27. This includes a left segment 28and a right segment 29. The motor in conjunction with the pulley andcable segments serve to transport the carriage from a center position inwhich it is now shown to extreme left and right printing positions.

Referring now to FIG. 2, the cables are coupled to carriage 13 through apulley arrangement 31 which is mounted on an axle 32 which in turn ismounted for rotation on carriage 13. Cable segments 28 and 29 are.wrapped around the two grooves of pulley 31 in oppo site directions asillustrated with their remaining free ends coupled to the frame 10; inthe case of segment 28 to resilient fastener 33, and in the case ofsegment 29 fixed fastener '34. Fastener 33 is illustrated in greaterdetail in FIG. 4 and includes a sleeve 36 which is resiliently biasedagainst frame 10 by a spring 37. In the case of segment 29 and fastening34 as illustrated in FIG. 5, there is a fixed fastening to frame 10.Spring 37 provides for the takeup of any slack in either of the cableswhich might occur due to long term temperature drift. While such longterm drift does not have the effect of shifting the registration ofprinting positions one with respect to the other, it may occur uniformlyacross the entire line ofprinting. Cable segments 28 and 29 are changedin direction by the idler pulleys 38 in the case of segment 28 andpulleys 39 in the case of cable segment 29, both of which are affixed toframe 10 as best shown in FIG. 1.

Although the pulley arrangement 31 is believed to be a preferable methodof attaching the cable segments 28 and 29, it would, of course, also bepossible to permanently attach the cable segments directly to thecarriage.

As is more clearly illustrated in FIG. 3 pulley 26 has a helicallygrooved rim around which the cable segments 28 and 29 are wrapped. Anend of cable segment 29 is affixed to the rim at point 41 as shown inFIG. 3 and the end of cable segment 28 is affixed to the rim at point42. The cable, as illustrated with the carriage 13 in its centerposition, has equal lengths of each segment in the grooves of thepulley. This is necessarily so if the entire lengths of the cablesegments 28 and 29 are to be equal. As the carriage is driven, asillustrated by the arrows in FIG. 2, to either the left or right extremepositions, a substantially greater length of one segment than the otherwill be accommodated or wrapped about pulley 26.

The provision of equal length cable segments and the details of theforegoing mounting or coupling of the carriage to the motor 22 providefor a compensation of 5 temporary mechanical drift due to, for example,the stretching of the cable caused by the intermittent motion of thecarriage. With the high speeds and high accelerations and decelerationsobtainable by the servo system used in conjunction with the presentinvention this is especially critical.

1 claim:

1. A high-speed printer for printing on a record medium comprising; amovable carriage for carrying a printing unit along a predetermined lineof printing with respect to said record medium said carriage includingfirst pulley means mounted for rotation on an axle mounted for rotationon said carriage; means for intermittently transporting said carriageand said printing unit to stationary printing positions along said lineof printing, said carriage being movable from a center position toextreme left and right positions, such transporting means including amotor, second pulley means driven by said motor; a frame foraccommodating said carriage and motor; cable means coupling said secondpulley means to said carriage, said cable means being divided into twosegments of equal length each of said segments having an end affixed tosaid second pulley means, said second pulley means having peripheralwrapping surfaces for wrapping equal lengths of said two segments onsaid surfaces when said carriage is in said center position, and forrespectively accommodating a substantially greater length of one segmentthan the other when said carriage is in one of said extreme positionssaid two segments being respectively wrapped around such pulley means inopposite directions, the other ends of said two segments being affixedto said frame, at least one of said ends being affixed to said frame byresilient means biased to provide a continuous tension in said cablesegments.

2. An arrangement for positioning a printing unit at predeterminedlateral printing positions relative to a recording medium in a highspeed'printer comprising, a frame arrangement associated with said highspeed printer, a carriage member for supporting said printing unit inoperative relationship to said recording medium, means operativelyassociated with said carriage member and said frame arrangement fordefining a path of travel of said printing unit in a substantiallylateral direction reative to said recording medium, a motor supported infixed relationship relative to said frame arrangement, a first pulleymember rotatably supported on said carriage member and adapted formovement with said carriage member in said lateral direction relative tosaid recording medium, a second pulley member drivingly connected to theoutput shaft of said motor, a first length of cable fixed at one endthereof to said second pulley member and at the other end thereof tosaid frame arrangement, said first length of cable being operativelyentrained about said first pulley member for transporting said carriagemember and said printing unit to one lateral extreme of said recordingmedium when said motor is driven in a first direction of rotation, asecond length of cable substantially equal in length to said firstlength fixed at one end thereof to said second pulley member and at theother end thereof to said frame arrangement said second length of cablebeing operatively entrained about said first pulley member fortransporting said carriage member and said printing unit to the otherlateral extreme of said recording medium when said motor is driven in asecond direction of rotation, and means for energizing said motor inpredetermined directions of intermittent rotation for reducing theeffective length in one of said lengths of cable between said secondpulley member and said frame arrangement and for correspondinglyincreasing the effective length in the other end of said lengths ofcable between said second pulley member and said frame arrangement forproducing a proportional movement of said carriage member and said printmember in said lateral direction.

3. Apparatus according to claim 2 wherein, said second pulley memberincludes surfaces for peripherally wrapping said equal lengths of saidfirst and said second lengths of cable when said print member is in asubstantially central lateral position and for respectivelyaccommodating a substantially greater length of one segment than theother when said print member is in one of said extreme positions.

4. Apparatus according to claim 2 further including, spring means forresiliently connecting at least one of the ends of said lengths of saidcable to said frame arrangement for maintaining a continuous tension ineach of said lengths of said cable.

1. A high-speed printer for printing on a record medium comprising; amovable carriage for carrying a printing unit along a predetermined lineof printing with respect to said record medium said carriage includingfirst pulley means mounted for rotation on an axle mounted for rotationon said carriage; means for intermittently transporting said carriageand said printing unit to stationary printing positions along said lineof printing, said carriage being movable from a center position toextreme left and right positions, such transporting means including amotor, second pulley means driven by said motor; a frame foraccommodating said carriage and motor; cable means coupling said secondpulley means to said carriage, said cable means being divided into twosegments of equal length each of said segments having an end affixed tosaid second pulley means, said second pulley means having peripheralwrapping surfaces for wrapping equal lengths of said two segments onsaid surfaces when said carriage is in said center position, and forrespectively accommodating a substantially greater length of one segmentthan the other when said carriage is in one of said extreme positionssaid two segments being respectively wrapped around such pulley means inopposite directions, the other ends of said two segments being affixedto said frame, at least one of said ends being affixed to said frame byresilient means biased to provide a continuous tension in said cablesegments.
 2. An arrangement for positioning a printing unit atpredetermined lateral printing positions relative to a recording mediumin a high speed printer comprising, a frame arrangement associated withsaid high speed printer, a carriage member for supporting said printingunit in operative relationship to said recording medium, meansoperatively associated with said carriage member and said framearrangement for defining a path of travel of said printing unit in asubstantially lateral direction reative to said recording medium, amotor supported in fixed relationship relative to said framearrangement, a first pulley member rotatably supported on said carriagemember and adapted for movement with said carriage member in saidlateral direction relative to said recording medium, a second pulleymember drivingly connected to the output shaft of said motor, a firstlength of cable fixed at one end thereof to said second pulley memberand at the other end thereof to said frame arrangement, said firstlength of cable being operatively entrained about said first pulleymember for transporting said carriage member and said printing unit toone lateral extreme of said recording medium when said motor is drivenin a first direction of rotation, a second length of cable substantiallyequal in length to said first length fixed at one end thereof to saidsecond pulley member and at the other end thereof to said framearrangement said second length of cable being operatively entrainedabout said first pulley member for transporting said carriage member andsaid printing unit to the other lateral extreme of said recording mediumwhen said motor is driven in a second direction of rotation, and meansfor energizing said motor in predetermined directions of intermittentrotation for reducing the effective length in one of said lengths ofcable between said second pulley member and said frame arrangement andfor correspondingly increasing the effective length in the other end ofsaid lengths of cable between said second pulley member and said framearrangement for producing a proportional movement of said carriagemember and said print member in said lateral direction.
 3. Apparatusaccording to claim 2 wherein, said second pulley member includessurfaces for peripherally wrapping said equAl lengths of said first andsaid second lengths of cable when said print member is in asubstantially central lateral position and for respectivelyaccommodating a substantially greater length of one segment than theother when said print member is in one of said extreme positions. 4.Apparatus according to claim 2 further including, spring means forresiliently connecting at least one of the ends of said lengths of saidcable to said frame arrangement for maintaining a continuous tension ineach of said lengths of said cable.